血液能量平衡指标对高产奶牛产后卵巢静止的影响

本试验旨在确立能量平衡对奶牛产后卵巢静止的作用,为今后预防该病提供科学依据。从黑龙江省某集约化牛场随机选取产后14~21d奶牛80头(年龄2~4岁,胎次1~3次,泌乳量(34.82±9.51)kg/d),跟踪观测至产后60~90d,进行奶牛发情鉴定,结合B超观察与生殖激素检测从观测奶牛中选出卵巢静止与发情奶牛各16头。对2组奶牛产后14~21d和60~90d的血浆能量代谢及肝功能指标进行了统计比较。结果显示:产后60~90d卵巢静止奶牛血浆β-羟丁酸和游离脂肪酸含量高于发情奶牛(P0.05),血浆促卵泡素、雌二醇和孕酮浓度极显著低于发情奶牛(P0.01);根据受试者工作特征曲线分析确定产后14~21d血浆β-羟丁酸0.69 mmol/L、游离脂肪酸0.52mmol/L作为产后卵巢静止预警值,灵敏度和特异度分别为85.7%和83.30%,92.3%和86.70%,产后60~90d2项指标的预警值分别为0.42,0.17mmol/L。奶牛产后14~21d与60~90d血浆β-羟丁酸和游离脂肪酸浓度超过预警值,奶牛产后发生卵巢静止的风险会增大。     

奶牛乳房炎的治疗方法

奶牛乳房炎是乳腺受到物理、化学、微生物刺激所发生的一种炎性变化.本病以乳汁的理化性改变为主,由多种非特定的病原微生物引起,不仅影响产奶量、牛乳质量、延长产后发情和妊娠时间,严重时还能使奶牛泌乳机能丧失而被淘汰,是世界奶牛业的主要危害因素之一[1-3].笔者根据多年的治疗经验,总结如下.     

Experimental Corynebacterium pseudotuberculosis mastitis in dairy cows

The inoculation of 2000 colony-forming units of Corynebacterium pseudotuberculosis into one teat canal of each of three cows resulted in severe, chronic, pyogranulomatous mastitis. Within three days the cows had a reduced haematocrit, haemoglobin concentration and red cell count. The anaemia was initially normocytic, normochromic and non-regenerative, and was associated with a brief peak of neutrophilia; a regenerative response became evident two to three weeks later. Clinical signs of mastitis appeared seven to 14 days after the inoculation, with a peak of high fever, more severe anaemia, a second peak of neutrophilia and the complete cessation of milk production from all quarters; extensive and severe pyogranulomatous mastitis developed in the inoculated quarters. No other lesions were detected postmortem, and C pseudotuberculosis was cultured from the affected quarters but not from the supramammary lymph nodes and viscera.     

控制奶牛乳房炎的饲料添加剂

1 维生素E和硒 近年来的研究表明,乳房炎的感染受血浆维生素E和硒水平的影响。在日粮中添加维生素E和硒能够提高乳腺对感染的天然抵抗力。维生素E具有抗氧化作用,是所有脂类膜必不可少的组成部分,可消除细胞膜上的自由基,从而保护中性粒细胞的细胞膜免受自由基的攻击和过氧化损伤。维生素E对机体的免疫反应有重要影响,它不仅能增强机体的体液免疫反应,而且能提高细胞免疫功能和嗜中性白细胞杀伤金黄色葡萄球菌和大肠杆菌的能力。众多试验证     

Nutritional factors that regulate ovulation of the dominant follicle during the first follicular wave postpartum in high-producing dairy cows

During recent decades, milk production per cow has increased drastically due to improved management, nutrition, and genetic selection; however, the reproductive performance of high-producing dairy cows has been declining. One of the factors responsible for this low reproductive performance is negative energy balance (NEB). NEB affects the onset of first ovulation in early postpartum cows. It is generally accepted that early first ovulation positively relates to the resumption of normal ovarian function, first service, and conception rate in dairy cows. Hence, delayed first ovulation has a negative impact on subsequent fertility. The metabolic condition of cows in NEB shifts to catabolic metabolism, which in turn causes increased plasma growth hormone and non-esterified fatty acid concentrations and decreased plasma insulin-like growth factor-1, insulin, and glucose concentrations. On the other hand, plasma β-carotene concentrations decrease throughout the dry period and reach their nadir in about the first week postpartum, and this change reflects energy balance during the peripartum period. β-Carotene plays a role independently of vitamin A in the reproductive performance of dairy cows, and the positive relationship between supplemental β-carotene and reproductive function has been demonstrated in many studies during the past decades. However, β-carotene content in corn silage, which is a popular main feed in high-producing dairy cows, is very low. This review describes nutritional factors related to ovulation during the first follicular wave postpartum in dairy cows.     

奶牛乳汁外泌体中乳房炎抗性相关microRNA的筛选与功能分析

奶牛乳汁外泌体中的microRNA(miRNA)在乳腺癌、炎症和其他乳腺疾病发生时起着关键的调控作用,为了解及分析乳汁外泌体中可能存在的参与奶牛乳房炎抗性的miRNA,以健康牛及乳房炎奶牛乳腺组织差异表达miRNA为背景,结合目前已知的奶牛乳汁外泌体miRNA,利用Targetscan、miRDB、miRanda、Vesiclepedia、DAVID等生物信息学分析系统及数据库系统,筛选奶牛乳汁外泌体中可能参与奶牛乳房炎抗性的miRNA,并对其序列保守性、候选靶基因及靶基因参与的调控功能通路等进行预测与分析。结果表明,健康奶牛与乳房炎奶牛乳腺组织中存在显著表达差异的miRNA 29个;Vesiclepedia数据库和NCBI检索文献共获得奶牛乳汁外泌体中的miRNA 66个,其中miR-223、miR-125b、miR-378b在两数据中共存,并在人与奶牛及其他哺乳动物之间高度保守。候选靶基因的KEGG功能通路分析显示,MAPK,p53、PI3K-Akt及miRNA的癌症作用、内质网蛋白加工、溶酶体和细胞凋亡等通路均被显著富集。表明外泌体中存在的3个miRNA对奶牛乳房炎发生时的炎症反应及免疫应答均可起重要调控作用,但其具体分子机制仍有待进一步验证。研究结果可为奶牛乳房炎分子辅助选择标记的筛选以及跨物种机体免疫调控的影响因素及作用机制研究提供参考。     

Production effects related to mastitis and mastitis economics in dairy cattle herds

Mastitis is the most prevalent production disease in dairy herds world-wide and is responsible for several production effects. Milk yield and composition can be affected by a more or less severe short-term depression and, in case of no cure, by a long-acting effect, and, sometimes, an overlapping effect to the next lactation. Summary values in the literature for losses of milk production were proposed at 375 kg for a clinical case (5% at the lactation level) and at 0.5 kg per 2-fold increase of crude SCC of a cow. Due to the withdrawal period after treatment, composition changes in milk can almost be neglected in economic calculations. Lethality rate for clinical mastitis is very low on the average, while anticipated culling occurs more frequently after clinical and subclinical mastitis (relative risk between 1.5 and 5.0). The economics of mastitis needs to be addressed at the farm level and, per se, depends on local and regional epidemiological, managerial and economic conditions. To assess the direct economic impact of mastitis, costs (i.e. extra resource use) and losses (i.e. reduced revenues) have to be aggregated. To support decision making for udder health control, it is necessary to use a marginal approach, based on the comparison of the losses avoided and the additional costs of modified plans, compared to the existing ones.     

Relationships between the first ovulation postpartum and polymorphism in genes relating to function of immunity, metabolism and reproduction in high-producing dairy cows

The decrease in fertility and conception rates of high-producing dairy cows is one of the major negative impacts for today's producers. The recovery of ovarian activity postpartum is affected by the status of immunity, metabolism and reproduction and plays a critical role in subsequent fertility after parturition in the cow. In the present study we investigated the relationships between polymorphisms in genes relating to the above functions and the first postpartum ovulation as a marker of the recovery of ovarian function in the cow. In immune function related-factors, the occurrence of first postpartum ovulation within 3 weeks in the C/C genotypes of tumor necrosis factor α (TNFα) exon (55.4%) and the A/G genotypes of TNFα promoter (55.4%) was significantly higher than that in T/T genotypes of TNFα exon (14.3%) and A/A genotypes of TNFα promoter (14.3%). Moreover, anovulatory cows with the T/T genotype of TNFα exon and the A/A genotype of TNFα promoter tended to have a prolonged days open compared with those of the other genotypes of TNFα polymorphisms. In metabolic function-related factors, ovulatory and anovulatory cows had a different distribution for alleles of the growth hormone receptor, but there were no significant differences in genotype and allele frequency of insulin-like growth factor-I polymorphism. No significant relationships were found between ovarian function after parturition and polymorphisms for reproduction-related genes. In conclusion, polymorphisms of TNFα gene both in exon and promoter regions have a strong association with the early first ovulation within 3 weeks after parturition in the high-producing dairy cow. Taken together, polymorphisms of TNFα gene could be strongly related to early first ovulation after parturition, thus being an effective tool of selection for improving reproductive performance in the high-producing dairy cow.     

Loss in milk yield and related composition changes resulting from clinical mastitis in dairy cows

Relationships between clinical mastitis and milk yield and composition in dairy cows were reviewed. Requirements for inclusion were: data had to be collected after 1975; dependent variables for milk yield and milk composition had to be defined at the cow level; mastitis cases had to be defined by clinical signs, and at least 250 lactations had to be considered. Twenty studies dealing with milk-yield loss and, for four of them, also with related composition changes were selected. Study populations, design of data collection, and analysis methods differed widely between studies. As expected from these differences – but also due to structural-variation factors such as type of pathogen, animal and production level – estimates for milk-yield losses differed in average magnitude and pattern. Literature data regarding changes in milk-fat % and total-protein % changes were contradictory. Critiques of materials and methods allowed us to propose some final recommendations for values to be used as basic inputs in economic calculations of losses caused by mastitis.     

Hormonal interrelationships in postpartum suckled dairy cows.

Three cross-bred cows calved in March and April and were followed until day 62 after parturition. Each animal was suckled by 2 calves ad libitum. All calves were removed from the cows on day 55 after parturition. Blood was collected 3 times per day from the jugular vein by venipuncture. On 4 occasions after parturition--i.e. days 7-8, 21-22, 35-36 and 49-50, the cows were bled through a jugular venous catheter every 30 min during the 24 h. The plasma samples were analyzed for the content of 15-keto-13,14-dihydro-PGF2 alpha (main PGF2 alpha metabolite), LH, prolactin, cortisol and progesterone by radioimmunoassay methods. The concentration of PGF2 alpha increased from 280 to 730 pmol/l within the last 4 days before parturition. The highest geometric mean was 3106 pmol/l on the day of parturition. Thereafter a steady decrease of PGF2 alpha metabolite concentration was seen until day 21 when it reached plateau at 148 pmol/l. In all cows plasma LH concentrations increased significantly (P < 0.05) from about 1.6 micrograms/l on days 7-8 to 2.4 micrograms/l on days 21-22 post partum. The frequency of LH pulses showed no tendency to increase as the postpartum period progressed and averaged 6.5 pulses/24 h. Mean plasma LH concentrations increased from 2.1 micrograms/l 2 days before weaning to 3.2 micrograms/l 2 days after weaning (P < 0.05). LH peaks occurred less frequently in association with prolactin and cortisol peaks than in their absence. A partial positive correlation between PGF2 alpha metabolite and cortisol (r = 0.30) was found on days 7-8 post partum. Correlation between prolactin and cortisol on days 7-8 and 21-22 post partum was also positive (r = 0.20 and r = 0.27, respectively). There was a negative correlation between LH and cortisol on days 7-8 (r = -0.27) and days 49-50 (r = -0.21) post partum. The first and short progesterone increase observed after weaning was terminated in conjunction with PGF2 alpha metabolite peaks.     

Prototheca zopfii mastitis in a herd of dairy cows

Mastitis caused by the colourless alga Prototheca zopfii was diagnosed in 17 of 120 cows in a dairy herd. Infection occurred in animals varying from 3–14 years old and was present in one to four quarters of each cow.

Nine cases were associated with clinical mastitis characterised by the presence in milk of flakes or small clots. Somatic cell counts consistent with subclinical mastitis (>500 × 10³ cells/ml) were recorded in five of the eight remaining cows.

Histological examination of udder tissue showed the presence of granulomatous lesions associated with the presence of Prototheca.

The problem was identified and controlled by repeated microbiological examination of milk samples from all lactating cows and immediate culling of infected animals.

P. zopfii was also recovered from environmental water samples on this farm. It is suggested that infection may have occurred as a result of teat sores caused by trauma from a milking machine, and the tendency for cows to lay down on a race, the surface of which was sometimes flooded by drain water in which Prototheca were present.     

Prototheca zopfii mastitis in a herd of dairy cows

Mastitis caused by the colourless alga Prototheca zopfii was diagnosed in 17 of 120 cows in a dairy herd. Infection occurred in animals varying from 3-14 years old and was present in one to four quarters of each cow. Nine cases were associated with clinical mastitis characterised by the presence in milk of flakes or small clots. Somatic cell counts consistent with subclinical mastitis (>500 x 10(3) cells/ml) were recorded in five of the eight remaining cows. Histological examination of udder tissue showed the presence of granulomatous lesions associated with the presence of Prototheca. The problem was identified and controlled by repeated microbiological examination of milk samples from all lactating cows and immediate culling of infected animals. P. zopfii was also recovered from environmental water samples on this farm. It is suggested that infection may have occurred as a result of teat sores caused by trauma from a milking machine, and the tendency for cows to lay down on a race, the surface of which was sometimes flooded by drain water in which Prototheca were present.     

Relationships between insulin-like growth factor-I,milk yield,body condition score,and postpartum luteal activity in high-producing dairy cows

The relations between body condition score (BCS), milk yield, serum insulin-like growth factor-I (IGF-I) profile, and luteal activity were investigated in postpartum dairy cows. Seventy-one healthy high-producing multiparous Holstein cows were subjected to transrectal ultrasound scanning twice weekly from the first to the eighth week postpartum. Blood samples were collected twice weekly to measure serum progesterone (P4) and every 2 weeks to detect serum IGF-I concentrations. BCS was monitored weekly after calving. Cows with serum P4 concentrations ≥1 ng/ml on at least two consecutive samplings were considered to have commenced luteal activity. Commencement of luteal activity (C-LA) was observed earlier than 45 days postpartum in 71.8% of cows while 28.2% showed C-LA later than 45 days. Prolonged luteal phase was the most common abnormal pattern of luteal activity observed. Cows with a C-LA earlier than 45 days postpartum had higher (P ≤ 0.05) mean serum concentrations of IGF-I than those with later C-LA. In addition, cows which showed C-LA earlier than 45 days postpartum had more optimal productive indices including shorter calving to conception interval and calving to first service interval (P ≤ 0.05), and fewer services per conception (P = 0.07). C-LA was significantly later in cows that lost more than 0.5 BCS units within 3 weeks postpartum than in those that lost less than 0.5 units BCS during the same interval (P = 0.02). We conclude that high-producing dairy cows with higher postpartum serum IGF-I concentrations have earlier commencement and normal luteal activity, and better reproductive performance. Severity and duration of BCS loss adversely affect commencement of luteal activity.     

Pathological and microbiological characterization of mastitis in dairy cows

Mastitis may be caused by a wide range of microorganisms able to induce distinct lesions in mammary tissues. This study aims to characterize the gross and microscopic features of mastitis in dairy cows and to correlate them with the pathogens involved. The udders of slaughtered dairy cows were inspected and milk samples from each mammary quarter or fragments of the parenchyma were sent for microbiological analysis, and tissue collected for histopathological evaluation. A total of 148 cows and 592 mammary quarters were collected. From these, 432 quarters (73%) had mastitis and in 160 (27%), no changes were observed. Mastitis was classified into seven patterns based on the histopathological findings, of which mixed, lymphoplasmacytic, and suppurative mastitides were the most prevalent with 35.9% (155/432), 27.1% (117/432), and 14.3% (62/432) of the cases, respectively. These patterns were associated with the same set of pathogens: Streptococcus spp., coagulase-negative Staphylococcus (CNS), Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, and Corynebacterium bovis. The pyogranulomatous pattern represented 7.2% (31/432) of the cases with distinct distribution based on the agent involved, mostly S. aureus and Nocardia sp. Abscedative mastitis accounted for 6.0% (26/432) of the cases; it was characterized by multiple abscesses in the parenchyma and was mainly caused by Trueperella pyogenes. Necrosuppurative mastitis represented 5.8% (25/432) of the cases which were characterized by severe parenchyma necrosis and were caused by bacteria such as CNS and Escherichia coli. The granulomatous pattern represented 3.7% (16/432) of the cases and was occasionally associated with Mycobacterium sp.

     

Automated detection of estrus and mastitis in dairy cows

The development and test of detection models for oestrus and mastitis in dairy cows is described in a PhD thesis that was defended in Wageningen on June 5, 2000. These models were based on sensors for milk yield, milk temperature, electrical conductivity of milk, and cow activity and concentrate intake, and on combined processing of the sensor data. The models alert farmers to cows that need attention, because of possible oestrus or mastitis. A first detection model for cows, milked twice a day, was based on time series models for the sensor variables. A time series model describes the dependence between successive observations. The parameters of the time series models were fitted on-line for each cow after each milking by means of a Kalman filter, a mathematical method to estimate the state of a system on-line. The Kalman filter gives the best estimate of the current state of a system based on all preceding observations. This model was tested for 2 years on two experimental farms, and under field conditions on four farms over several years. A second detection model, for cow milked in an automatic milking system (AMS), was based on a generalization of the first model. Two data sets (one small, one large) were used for testing. The results for oestrus detection were good for both models. The results for mastitis detection were varying (in some cases good, in other cases moderate). Fuzzy logic was used to classify mastitis and oestrus alerts with both detection models, to reduce the number of false positive alerts. Fuzzy logic makes approximate reasoning possible, where statements can be partly true or false. Input for the fuzzy logic model were alerts from the detection models and additional information. The number of false positive alerts decreased considerably, while the number of detected cases remained at the same level. These models make automated detection possible in practice.     

Intramammary application of ozone therapy to acute clinical mastitis in dairy cows

The infusion of ozone into the inflamed quarter of cows with clinical mastitis was performed and the efficacy of ozone therapy was evaluated. Ozone was infused into the inflamed quarter via a teat canal using ozone gas generating equipment. Nineteen Holstein cows with acute clinical mastitis were divided into two groups: 15 cows treated with ozone therapy, and 4 cows treated with antibiotic therapy. Systemic and local clinical signs, California Mastitis Test scores, the mastitis causing pathogens, electronic conductivity of milk, and somatic cell counts in milk from ozone- and antibiotic-treated quarters, were compared between the groups. Sixty percent (9/15) of cows with acute clinical mastitis treated with ozone therapy, did not require any antibiotics for recovery. This newly developed ozone therapy method was proven to be effective, safe, and cost effective, and carries no risk of drug residues in milk.     

Gene expression patterns in the ventral tegmental area relate to oestrus behaviour in high-producing dairy cows

Reduced oestrus behaviour expression or its absence (silent oestrus) results in subfertility in high-producing dairy cows. Insight into the genomic regulation of oestrus behaviour is likely to help alleviate reproduction problems. Here, gene expression was recorded in the ventral tegmental area (VTA) of high milk production dairy cows differing in the degree of showing oestrus behaviour (H - highly expressing versus L - lowly expressing), which was then analysed. Genes regulating cell morphology and adhesion or coding for immunoglobulin G (IgG) chains were differentially expressed in VTA between cows around day 0 and 12 of the oestrus cycle, but only in cows that earlier in life tended to show high levels of oestrus behaviour (H0 versus H12). The comparisons between H and L groups of cows also revealed differential expression of several genes (e.g. those of the IgG family or encoding for pro-melanin-concentrating hormone). However, any significant changes in VTA genes expression were detected in the comparison of L0 versus L12 cows. Altogether, the genes expression profile in VTA of cows highly expressing oestrus behaviour changes together with phases of the oestrus cycle, while in case of cows expressing oestrus behaviour lowly it remains stable. This supports the existence of genomic regulation by centrally expressed genes on the expression of oestrus behaviour in dairy cows.     

Coxiella burnetii seropositivity is highly stable throughout gestation in lactating high-producing dairy cows

The aims of this study were to analyse, in high-producing dairy cows, plasma Coxiella burnetii antibody titres and seroconversion throughout gestation, along with possible factors affecting such titres. The study was performed on 65 lactating pregnant non-aborting animals in a commercial Holstein-Friesian dairy herd in northeastern Spain. Blood samples for antibody determinations were collected on days 40, 90, 120, 150, 180 and 210 of gestation. By General Linear Model (GLM) repeated measures analysis of variance, the effects of milk production and reproductive variables as well as Neospora caninum-seropositivity on C. burnetii antibody levels for all animals and for seropositive animals were established. Significant effects were observed of day of gestation, parity and N. caninum-seropositivity (between subject effects) on the C. burnetii antibody levels recorded for the whole population of animals throughout the gestation period. C. burnetii antibody levels were higher in primiparous than in multiparous cows, with titres in primiparous cows diminishing during the post-partum period. In seropositive cows, significant effects were observed of milk production and inseminating bull on gestational C. burnetii antibody levels. When the data were subjected to binary logistic regression considering C. burnetii-seropositivity as the dependent variable, the resultant odds ratios indicated that the likelihood of C. burnetii-seropositivity was lower in N. caninum-seropositive animals (OR 0.12) compared to N. caninum-seronegative animals, and in multiparous cows (OR 0.12) compared to primiparous cows. In conclusion, Coxiella-infected dams remained seropositive during the whole gestation period, though primiparous cows showed a drop in antibody titres post-partum. No seronegative cow suffered seroconversion. Presence of both, N. caninum and C. burnetii antibodies in the same animal, was associated with a decrease in antibody titres against C. burnetii, perhaps indicating some cross-protection in animals infected by both pathogens.